The invention relates to filter elements, especially hollow filter elements, for the filtration of gaseous or liquid media as well as to a method of making such filter elements.
Filter cartridges constructed in the form of cylindrical hollow bodies are known. In order to be used, such filter cartridges are threaded into a support so as to have a vertical orientation. These known filter cartridges are distinguished in that they have a large surface area available for filtration.
The filter cartridges may be economically manufactured from metal powder using a sintering operation. Since the sintered metal has an inhomogeneous structure, however, the individual filter cartridges cannot provide an uniform filtering effect.
It is further known to arrange a plurality of wire cloths of different mesh one upon the other and to join the individual layers by sintering so as to form a filter plate. The filter plate is bent to the form of a cylindrical body and the abutting edges of the filter plate are then welded to one another. The hollow filter body obtained in this manner thus has a weld seam which extends along the entire length of the filter body. The filtering effect in the region of this weld seam is non-existent. In addition to this disadvantage, there exists the consideration that the production costs for a filter body of this type are very high.